Iron absorption from a malted cocoa drink fortified with ferric orthophosphate using the stable isotope58Fe as an extrinsic label

Abstract

1. The potential use of an extrinsic label to measure iron absorption from a ferric orthophosphate-fortified malted cocoa drink was examined by measuring the solubility of the FePO4 in 0·1 M-hydrochloric acid. 2. The validity of using the stable isotope 58Fe as an extrinsic label was tested by comparing Fe absorption by rats from wheat flour extrinsically-labelled with 58Fe or 59Fe. 3. Fe absorption from a malted cocoa drink (20 g powder made up with hot water) fortified with FePO4 (0·5 mg Fe/g powder) was measured in human subjects using 58Fe as an extrinsic label. Absorption was calculated by measuring unabsorbed 58Fe in faeces. Absorptions of Fe from the drink fortified with either FePO4 or ferrous sulphate were compared. The effect of the addition of ascorbic acid to the drink (1 mg/g powder) on Fe availability was also examined. 4. The effect of fasting on Fe absorption from the drink was determined in rats by giving the drink to fasting animals or shortly after they had consumed a small meal. 5. The FePO4 was totally soluble in 0·1 M-HCl and there were no differences in absorption between 58Fe- and 59Fe-labelled wheat flour. In the human experiment the proportion of Fe absorbed from the drink plus FePO4 and ascorbic acid was (mean with SE) 0·25 (0·02), from the drink plus FePO4 0·24 (0·02) and from the drink plus FeSO4 0·23 (0·03). Fasting had a significant effect on Fe availability; rats given the drink shortly after a small meal absorbed less than half as much Fe as those given the drink on a fasted stomach. 6. It was concluded that the FePO4 used to fortify the malted cocoa drink was as well absorbed as FeSO4 but that the high levels of absorption were a reflection of the fasting condition of the subjects. The level of ascorbic acid was not great enough to enhance the availability of the FePO4 any further.